1. Field of the invention
The present invention disclosed herein broadly relates to improvement of heat efficiency of a refrigeration system consisting of a plurality of refrigerating cycles, and more particularly relates to;
firstly improvement of heat efficiency of a refrigeration system consisting of a plurality of refrigerating cycles connected respectively to a plurality of refrigerant vapor lines, through each of which a refrigerant stream of a different evaporating temperature flows, respectively;
secondly improvement of heat efficiency of a refrigeration system consisting of a plurality of refrigerating cycles, each of which has a different condensing temperature or a different condensing pressure of refrigerant, and;
thirdly improvement of heat efficiency of chilling facilities for chilling liquid, into which a refrigeration system consisting of a plurality of refrigerating cycles is incorporated.
Further, the present invention includes improved refrigeration systems and improved chilling facilities used for chilling various kinds of fluid, especially for chilling malt cooling water, which is circulatedly used as coolant in a brewery for cooling hot malt juice before sent to a fermenting process.
2. Description of the Prior Art
Various kinds of liquids or gases are required to be chilled for finishing or further treating in food processing industries such as breweries, and they are generally chilled by individual refrigerating cycles provided and operated independently and separately each other, because ideas on integration of such individual refrigerating cycles to great extent have not been necessarily established yet.
A number of improved systems of heat utilization have been proposed, but they are only for the purpose of improving heat efficiency in an individual refrigerating cycle.
In food processing plants such as breweries, however, many kinds of refrigeration loads actually exist, and refrigerating temperatures are also classified to many temperature levels. Furthermore, each refrigeration load varies timewise and daywise in terms of magnitude and its ratio to the entire load.
Thus, an overall improvement of heat utilization should be attempted, considering a combination of a plurality of refrigerating cycles having individual refrigeration loads.
The following two systems have been known as the refrigeration systems to handle refrigeration loads of multiple temperatures and of great varieties as described above.
A refrigeration system has, as shown in FIG. 2, compressors 11, condensers 12, reservoirs 13, expansion valves 14 and evaporators 15. Evaporators 15 and compressors 11 are connected each other through a common refrigerant vapor line 16 for integration as the system.
The evaporating pressures in the respective evaporators are controlled by adjusting valve opening of an evaporating pressure regulator (EPR) 17, or by adjusting the flow rate of cooling medium such as cooling water, refrigerant etc. to be supplied to each condenser (heat exchanger) 12, while all of the compressors suck refrigerant gas at the pressure corresponding to the lowest evaporating temperature (in this case, -10 deg. C. (degrees Centigrade)) among the evaporating temperatures of the evaporators.
Another refrigeration system is comprised of a group of separate refrigerating cycles individually provided with necessary equipment such as a compressor, a condenser, a reservoir, etc. each of which refrigerating cycles is fixedly assigned to each particular refrigeration load.
A great deal of power is needed in the refrigeration system shown in FIG. 2, since all of the compressors have to suck refrigerant gas at the lowest evaporating temperature (-10 deg. C.). Additionally, a specific compressor out of compressors 11 may not be always selectively assigned to a specific load, and the optimization for sharing of loads in compressors is not feasible, resulting in higher power consumption at all.
In the refrigeration system shown in FIG. 3, when a compressor 11 is out of order, the whole of the refrigerating cycle related to the compressor becomes out of service. No backup means is available for any of the refrigerating cycle, either.